Electric heating apparatus



Nov. 3, 1925. 1,560,294

' H. GEISENHNER ELECRIC HEATING APPARATUS Filed Nov. 25, 1922 His JCI-t-tomcg.

Patented' Nov.' 3, 1925i.

UNITED STATES 1,560,294 PATENT OFFICE.

HENRY GEISENHNER, F SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELEC- TRIC COMP-ANY, A CORPORATION OF NEW YORK.

ELECTRIC HEATING APPARATUS.

Application filed November 25, 1922. Serial No. 603,333.

To ali who/1L it may concern:

Be it known that I, HENRY GEISENHNER,

a citizen of the United States, residing at Schenectady, in the county of Schenectady, 5 State of New York, have invented certain new and useful Improvements' in Electric Heating Apparatus, of which the following is a specification.

.My invention relates to electric heating apparatus, and particularly to such apparatus inwhich the heated articleitself is included in the heating circuit. One of the objects of the invention is the provision of simple, reliable and efficient apparatus ott' this character in which the articles to be heated may be autonmtically fed into the heating apparatus. y

More specifically my invention relates to apparatus for annealing metallic articles` such as armature conductors, in which a 'low voltage current of high value is passed through the article. In such heating apparatus forces are set up acting on the article due to the unequal densities of the magnetic flux in its vicinity. Thesel forces tend to distort the heated article. and in case thc article is relatively fragile it will be unable to withstand the forces when heated due to its weakened condition and will 30 consequently be bent into a curved forni.

In carrying out my invention I place a shield adjacent the heated article in such position as to equalize themagnetic field in its vicinity and thus neutralize the distorting forces. I also provide means for periodically moving the articles into heating position, the previously'heated article being thereby discharged.

For a more complete understanding of my invention reference should be had to the accompanying drawing in which Fig. 1 is a perspective view partially in .section of a. heating apparatus embodying my invention; Fig. 2 is an elevation view of a part of the feeding mechanism; While Fig. 3 is adiagrammatic view of a modified form of my invention. v

Referring to Figs. 1 and 2, in one form of my invention I provide a source of low voltage heating current consisting of a shell type transformer provided with a primary Winding 11 on its middle leg and having a single turn secondary winding encircling the primary Winding. The secondary winding comprises two heavy metallic members or bars 12 and 13 made of a suitable electrically conducting material, such as copper, which extend between the middle and outer legs of the' transformer shell respectively on opposite sides of the primary winding 11. These heavy conducting members or bars l2 and 13 are each pivoted atone end on a rod 1-1 which is secured on suitable brackets 15, only one of which is shown, attached to the body of the transformer. The pivoted ends of the bars 12 and 13 are electrically connected by suitable flexible laminated bars 16. The construction of the various features of the transformer so far mentioned is described and claimed in Patent No. 1.343,9;-i6 to Collins and therefore will not be described in detail. Secured to the free ends of the secondary bars 12 and 13 which are bent outward are heavy metallic terminal members 17 and 18 which are preferably corrugatedas shown to provide for the dissipation of excess heat. It Will be observed that the free ends 12 and 13 are movable in an uplward direction about the pivot 14. This movement is limited and the terminals 17 and 18 are constrained to take a predetermined path of movement by means of angle bars 20 and 2l secured in insulated relation to thel ends of bars 12 and 13 and having a limited range of movement in an upward direction in guides 22 and 23 respectively secured to the. transformer.

The article to be heated, shown as an armature bar 24,is moved into engagement with the terminals 17 and 18 so as to close ,an electric circuit between them, whereby the bar is heated by the heavy current paSSed through it. The bar 24 rests While in heating position on stationary supports or. tables 25 and 26 placed directly below the terminals 17 and 18 respectively. In moving the bar 24 into heating position the bar is first placed on the supports 25 and 26 a short distance from the ends of the te1minals.after which it is engaged by carriers or feeding members 27 and 28 and pushednnderneath the terminals 17 and 18. As the bar is pushed under the terminals, the terminals are raised slightly, moving about pivot 14, and rest on the bar so as to be held in electrically conduction relation with the barby their own Weight. As each bar is pushed under the terminals, the preceding bar which has been heated 1s pushed 0E the rear ends of supports 25 and 26 and falls into a receptacle 29 containing a suitable cooling bath such as water.

The feeding members 27 and 28 move in central, longitudinal guide slots 30 and 3l in the supports 25 and 26. Racks 32 and 33 are provided 011 the lower edges of members 27 and A28 respectively which racks are engaged by gear sectors 84 and 35 whereby reciprocating movement may be imparted to the feeding devices 27 and 28. The gear sectors 34 and 35 are rigidly secured to a transverse shaft 8G to which also-is secured central thereof a crank arm 37. This crank arm is operatively connected by means of a link 38 to a crank pin 39 carried by a worm gear 40. A suitable driving means is provided for the worm gear 40, such as an eleptric motor 41 bearing on its shaft a worm 42' which cooperates with the worm gear 40.

As the electric motor rotates, it will be .observed that through /the mechanism described the gear sec ors 34 and 85 will be moved back and forth through a definite angle whereby the feeding' members 27 and 28 will be reciprocated to and fro, toward and away from the terminals 17 and 18. The transformer and various other parts heretofore described are preferably mounted on a suitable supporting framework which as shown in the drawing may be made from angle iron.

Referring particularly to Fig. 2, onthe end of each terminal at its-lower edge is an insulated transverse section 45 having its outer edge curved so as to facilitate the insertion or pushing ofthe bar 24 underneath the terminal. These insulated sections are .provided to prevent electric contact of the bar wit-h the terminals until the bar has been pushed under the terminals. If these insulated sections were not provided, arcing and consquent burning of the parts would result from the poor or intermittent contact made as the bar is being pushed under the terminals. A central recess or .slot 45 is provided in the lower side of each terminal in which the cooperating feeding member moves in order to push the bar 24 past the insulated section 45.

In order toelect-rically insulatethe. bar 24 from the supports 25 and 26, and thus prevent a short circuit between the terminals 17 and 18 through the supporting framework of the apparatus, an insulated transverse section 46 is provided on the inner end of each support at its upper edge on which the bar rests while in heating position. This section 46 is shown provided with a lateral extension 47'whereby it is secured 'by an insulated plate 48 clamped on the extension by means of suitable insulated screws paing therethrough. Since the supports are each divided at their upper surfaces into two parallel faces or parts by the guide slots 30 'and 31 inwhich the carriers 27 and 28 move, it will be observed that two sets of insulated members 47 and 48 are provided for each support. Adjacent the ends of the insulated members 47 and 48 is an insulating block 49. The upper surfaces of members 46 and 48 and the insulating block 49 are all flush with each other and with the upper surface ofthe support. The inner end of each of the feeding members 27 and 28 is also provided with an i11- sulated section 5t) which engages the bar 24 in moving it into heating position.

In operating the heating apparatus as thus constructed and arranged, a number of the bars 24 to be heated may be placed on a table 5l which is secured to the transformer and conveniently located above the supports and26. 'The electric motor 41 operates continuously and moves the.' feeding members 27 and 28 back and forthin slots 50 and 8l. lVhen the feeding members reach their extreme outermost positions, as shown in dotted lines in Fig. 2, a bar 24 is placed b v the operator ou the supports and 2G in the insulating blocks 49 just in front of the feeding members 27 and 28. As the motor continues to operate, the feeding members are reversed and moved toward the terminals 17 and 18, moving the bar 24 with them. When the bar is being pushed under the terminals 17 and 18, it first rests on the insulated sections 48 so as to be insulated from the supports and engages the insulated sections 45 on the terminals. In its final heating' position, the bar rests on insulated sections 46 and is in electrically conducting relation with terininals 17 and 18. As each successive bar is pushed in it engages the previously heated bar, pushing it out and causing it to drop into the tank 29.

It will be observed that the bar 24 forms a part of a loop, carrying a current, whenm connectedvin the secondary circuit, which i loop is inter-linked by a .flux set up by the No current flowing in the loop. Now the flux density in the limited are-abounded by the loop is much greater than in the unlimited area outside of the loop.' This condition of `greater flux density on the inner side of all 115 the current carrying parts of the secondary circuit results in forces acting on these parts, including the bar 24, in an outward direction. I have found that due to the heavy current in the bar these forces are of such "in strength that when the bar is hot and consequently in a weakened condition, it -is bent outward in the shape of a bow. 1u order to overcome or neutralize these bending forces due to the unequal liux densities n" in the vicinity of the bar, I place a shield made of a suitable magnetic material or material having a high permeability, such as core iron, adjacent the bar. This shield .is ,suitably supported in position to eri-"fm table 51. -The effect of the shield is to forces which would otherwise act on the bar- 24 are thereby neutralized. The exact position of the 'shield 55 with relation to the bar 24 depends upon the strength of the unbalanced magnetic field in the vicinity of the bar. Its effect is made more pronounced by moving it nearer the bar. If the shield is placed too near, the bar will be bent in vard toward the shield. It may be adjusted to a suitable position to give the desired results by adding or removing washers 58 placed between it and the supporting brackets 56 and 'By means of this magnetic shield I am enabled to overcome any tendency for the bar to be distorted during the. heating operation.

In the modified form of my invention shown in Fig. 3 I have shown the application of the magnetic shield to au electric welding or soldering machine. This particular machine is adapted for making switch clip supports, such as used on switchboards. In making these supports a cylindrical stud 60 of electrically conducting` material, such as copper, is electrically soldered or welded to a rectangular head 61 made of similar material. This welding operation may be effected in any suitable manner, for example, by gripping the lug 60 in jaws 63 and 63 and then moving it into engagement with the head 61, whereby an electric heating circuit is closed from the low voltage secondary of the transformer 64.

I have found that the inequality in the magnetic ux densities in the vicinity of the heated parts may be sufficiently great to force the molten metal at the joint outward from between the stud and the head with the result that the weld is defective. I accordingly place the magnetic shield 65 adjacent the heated parts inside the loop formed by the secondary heating circuit. As shown, in this form of my invention the magnetic shield 65 may take the form of al pipe made of a suitable magnetic material, such as wrought iron. This form was selected due to the necessity of some cooling means for the shield, since it has atendency to be heated from induced currents. Preferably, cooling water is circulated through the jaws 63 and 63 and through the shield 65 whereby excessive temperatures in these parts are prevented. Obviously, in order to reduce the heating effect from the induced currents, the shield may be made of laminated core iron.

Although the magnetic shield particularly applicable to electric heatiig apparatus, it obviously has application to electr'- cal apparatus in general in the protection of' any current carrying member from distorting forces due to unequal magnetic flux densities in its vicinity. Protecting means of this character is particularly desirable during overloads or short circuits. For eX- ample, where two or more conductors are located near each other, shields may be placed between them to prevent their being thrown out vof place in case of excessive cui'- rent iow.

lVhile I have described my invention as embodied in concrete form -and as operating in a specific manner in accordance with the provisions of the patent statutes, it should be understood that I do not limit my invention thereto, since various modifications thereof will. suggest themselves to those skilled in the. art without departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

lAVhat I claim as new and desire to secure by Letters Patent of the United States, is,-

l. The combination Awith a current carrying member. of an electric circuit including said member` and a member having a high magnetic permeability placed in the loop formed by said circuit at such distance from said current carrying member that the magsaid loop at such distance from said current' carrying member that the magnetic field density adjacent the inner side of said eurrent carrying member isv reduced to the field density adjacent the outer side of said current carrying member.

3. An electric heater, comprising a transformer provided with low voltage secondary winding, means for connecting the article to be heated in circuit with said secondary winding,- and a member having a high mag netic permeability adjustably mounted between 'the article. and said transformer, said member being arranged to shunt a portion of the magnetic field on the inner side of' said article and thereby reduce the density of said field to the density on the outer side of said article.

et. An electric heater comprising a transformer provided with a secondary winding including parallel pivotally mounted conductor bars, said bars having two adjacent ends electrically connected and their opposite ends forming terminals, means for connecting the article to be heated to said terminals, and a member having a high magloo ltlf) lll) lneitic permeability adjustably mounted between said terminals, said member being adjusted with relation'to the inner side of said article so as to shunt a portion of the magnetic field and thereby' reduce the field density adjacent the inner side of said article to the same value. as thel field density on the outer side of said article.

An electric annealing machine comprising a transformer having a. low voltage secondary winding,` terminals for said secondary winding, and means comprising a feeding member moving back and forth toward and away from said terminals for periodically feeding an article to be heated into engagement with said terminals so as to be included in said secondary circuitand concurrently therewith discharging a previously heated article.

6. An electric annealing machine comprising a transformer having a low \-'ol,tage secondary winding, terminals for said secondary winding, a cooling bat-h adjacent said terminals, a feeding member movable toward and away from said terminals, and means comprising an electric motor for moving said feeding member away from said terminals to receive an article to be heated and toward said terminals to move said article. into engagement therewith so as to be included in said secondary circuit and concurrently therewith discharging a previously heated article into said bath. l d

7. An electric annealing machine comprising a transformer having a secondary winding provided with terminals movable in a vertical direction, supports under said terminals for the heated article, and feeding means for pushing the article under said termina-ls whereby the terminals are raised and an electric heating circuit thereby colnpleted through the article. i

8. An electric annealing machine com- 'mounted bars, said bars havin megane prising a transformer having a secondary winding provided with terminals movable in a vertical direction, supports under said terminals for the heated article, feeding means for ushing the article under said terminals w ereby the terminals are raised two adjacent ends electrically connected and their opposite ends forming terminals, Supports under said terminals, feeding members on said supports movable toward and away from said terminals, and a motor for 'actuating said feeding members so as, to push the article to be heated under said terminals and thereby close a heating circuit through the article.

l0. An electric annealing machine comprising a transfm-mer provided with a secondary winding including parallel pivotally two ends electrically connected and thelr opposite -ends forming termin-als, supports under said terminals, feeding members slidably mounted on said supports, gear racks carried by said members, a shaft, gear sectorsl secured to said shaft cooperating respectively with saidracks, and driving means for rocking said shaft whereby said feeding members are moved away from said terminals to receive an article to be heated and toward said terminals to push the article under said terminals and thereby close a heating circuit through the article.

AIn witness whereof, I have hereunto set Vmy hand this 24th day of November, 1922.

HENRY GEISENHNER.

soV 

